1. Field of the invention
The present invention relates to multiple lens imaging apparatuses each having a plurality of imaging units and to methods for setting exposure of the multiple lens imaging apparatuses. The present invention also relates to programs that cause a computer to execute the methods.
2. Description of the Related Art
Various kinds of multiple lens imaging apparatuses that enable three-dimensional (3D) imaging or panoramic imaging have been proposed as multiple lens imaging apparatuses each having multiple imaging units. In such multiple lens imaging apparatuses, identical imaging units are located to the right and left of each of the apparatuses, and images obtained simultaneously by the respective imaging units are subjected to composite processing to generate a stereo image realizing stereovision or a panoramic image.
Meanwhile, in each of multiple lens imaging apparatuses, each of imaging units has an iris and an iris adjustment mechanism that are controlled independently from the other imaging unit or units. Therefore, an amount of light is different between images from the respective imaging units, and a stereo image or a panoramic image generated from the images is substantially uncomfortable to view.
For this reason, a method of determining one exposure value based on comparison of exposure values between imaging units and a method of determining one exposure value based on comparison of image data obtained by imaging units have been proposed (see Japanese Unexamined Patent Publication Nos. 8 (1996)-029895 and 9 (1997)-084056, respectively). In addition, a method has been proposed wherein luminance data of an image obtained by a specific one of imaging units are compared with reference data and exposure of an imaging unit other than the specific imaging unit is adjusted based on a result of the comparison (see Japanese Unexamined Patent Publication No. 2000-341719).
However, in the methods described in Japanese Unexamined Patent Publication Nos. 8 (1996)-029895 and 9 (1997)-084056, each of the imaging units needs to calculate the exposure value independently. Therefore, the configuration of a corresponding multiple lens imaging apparatus becomes complex, and the apparatus becomes larger in size. In the method described in Japanese Unexamined Patent Publication No. 2000-341719, the exposure value set for one of the imaging units is used for the other imaging unit. Therefore, a corresponding apparatus can be prevented from becoming large in size. However, the calculated exposure value is not necessarily appropriate for the other imaging unit. Therefore, an image obtained by the other imaging unit may have a saturated area such as an area where white compression or black compression is observed.